[POWERPC] Fix irq flow handler for 4xx UIC

[linux-2.6-omap-h63xx.git] / arch / powerpc / sysdev / uic.c

diff --git a/arch/powerpc/sysdev/uic.c b/arch/powerpc/sysdev/uic.c
index ef8eb5bc6bba277269f3df8c82ac335b6d7559c3..22c219e448d4f95c46749278950ad5934b4dabf8 100644 (file)
--- a/arch/powerpc/sysdev/uic.c
+++ b/arch/powerpc/sysdev/uic.c
@@ -24,6 +24,7 @@
 #include <linux/spinlock.h>
 #include <linux/irq.h>
 #include <linux/interrupt.h>
+#include <linux/kernel_stat.h>
 #include <asm/irq.h>
 #include <asm/io.h>
 #include <asm/prom.h>
@@ -159,6 +160,64 @@ static struct irq_chip uic_irq_chip = {
        .set_type       = uic_set_irq_type,
 };
 
+/**
+ *     handle_uic_irq - irq flow handler for UIC
+ *     @irq:   the interrupt number
+ *     @desc:  the interrupt description structure for this irq
+ *
+ * This is modified version of the generic handle_level_irq() suitable
+ * for the UIC.  On the UIC, acking (i.e. clearing the SR bit) a level
+ * irq will have no effect if the interrupt is still asserted by the
+ * device, even if the interrupt is already masked.  Therefore, unlike
+ * the standard handle_level_irq(), we must ack the interrupt *after*
+ * invoking the ISR (which should have de-asserted the interrupt in
+ * the external source).  For edge interrupts we ack at the beginning
+ * instead of the end, to keep the window in which we can miss an
+ * interrupt as small as possible.
+ */
+void fastcall handle_uic_irq(unsigned int irq, struct irq_desc *desc)
+{
+       unsigned int cpu = smp_processor_id();
+       struct irqaction *action;
+       irqreturn_t action_ret;
+
+       spin_lock(&desc->lock);
+       if (desc->status & IRQ_LEVEL)
+               desc->chip->mask(irq);
+       else
+               desc->chip->mask_ack(irq);
+
+       if (unlikely(desc->status & IRQ_INPROGRESS))
+               goto out_unlock;
+       desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
+       kstat_cpu(cpu).irqs[irq]++;
+
+       /*
+        * If its disabled or no action available
+        * keep it masked and get out of here
+        */
+       action = desc->action;
+       if (unlikely(!action || (desc->status & IRQ_DISABLED))) {
+               desc->status |= IRQ_PENDING;
+               goto out_unlock;
+       }
+
+       desc->status |= IRQ_INPROGRESS;
+       desc->status &= ~IRQ_PENDING;
+       spin_unlock(&desc->lock);
+
+       action_ret = handle_IRQ_event(irq, action);
+
+       spin_lock(&desc->lock);
+       desc->status &= ~IRQ_INPROGRESS;
+       if (desc->status & IRQ_LEVEL)
+               desc->chip->ack(irq);
+       if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
+               desc->chip->unmask(irq);
+out_unlock:
+       spin_unlock(&desc->lock);
+}
+
 static int uic_host_match(struct irq_host *h, struct device_node *node)
 {
        struct uic *uic = h->host_data;
@@ -173,7 +232,7 @@ static int uic_host_map(struct irq_host *h, unsigned int virq,
        set_irq_chip_data(virq, uic);
        /* Despite the name, handle_level_irq() works for both level
         * and edge irqs on UIC.  FIXME: check this is correct */
-       set_irq_chip_and_handler(virq, &uic_irq_chip, handle_level_irq);
+       set_irq_chip_and_handler(virq, &uic_irq_chip, handle_uic_irq);
 
        /* Set default irq type */
        set_irq_type(virq, IRQ_TYPE_NONE);